5 Replies Latest reply on May 13, 2008 2:23 AM by Gabrie

    VMFS and blocksize  SAN performance?

    Gabrie Master



      For a particular VM I need 2x 1,6Tb disk. So I thought of creating two LUNs of 2Tb each with a 4Mb blocksize and put the VMDKs on them. Now I'm having a discussion with the SAN admin about the blocksize. We both agree that ESX can do sub-blocks, so if you have a 32kb file on you VMFS volume, it will not occupie a whole block of 4Mb, which is very nice.









      But when a VM, acting as a file server, with VMDK on a 4Mb block VMFS volume, has to read files, what size is the block that will be read from SAN? Will this VM cause 4Mb block reads from the SAN even for very small files? This would cause quite a stress on our SAN, wouldn't it?